Inside a mason bee nest
Harvesting cocoons from Corn Quicklock trays is fun. You open two pieces of interlocking trays and you see what is inside. Every row tells its own story and often it is a very different from the adjacent nesting tunnel. It is great to see bees at work, but it is very exciting to see what they have produced and to see what other insects are using these nesting tunnels as their home.
This pink larvae has a brown head capsule. It feeds on any detritus and pollen in the tunnel. If left inside over the winter, it can chew through cocoons and destroy your bees. After it has spun its cocoon, it emerges again during the early summer as a moth. I remove these grubs from the nest as I harvest mason bee cocoons.
|Here is the larvae spinning its web for its overwintering period.|
This morning I received an email from Norm
Subject: cocoon removal
“ I have the cardboard tubes with liners.
Is it possible to remove the cocoons from this type nest?”
Yes it is possible. First try pulling out the liners. If the liner is dry, you can remove the liner and replace the tube with a clean liner. Unfortunately if there is any moisture, the liner absorbs moisture and breaks when you try and remove the liner. If this happens, the cardboard tube has to be unraveled to get the cocoons out.
This nesting tray contains 5 nesting tunnels. The upper nesting tunnel contains cocoons with a mud partition between each cocoon. The mud plug at the left hand side of the nesting tray indicates the entrance /exit. The larger or female cocoons are at the back of the tunnel (RHS). Note in the next two nesting tunnels, there are quite a number of compartments, not with a cocoon, but with a pollen lump.
The presence of a pollen lump means that the bee larvae died and did not continue its development into an adult bee. This can be caused by disease, but can also be caused by cool weather. Young bees need warmth to feed. A two week spell of cold weather usually means the demise of these bees. Unfortunately in this case, the pollen lumps were at the far end of the tunnel and these are the female bees.
This year, many people were not able to produce many mason bee cocoons. I am sure the weather played a big part in this story.
NOTE: Usually I would not disturb the cocoons and the pupae like the resin bees, but close up the nest and set the nest outside. The reddish frass and the multiple pupae in one cell, looks like it came from a predator of some kind and I would remove it from the nesting tunnels.
Photo #1. Joe S. from Burnaby, BC showed me this interesting occupant of his Beediverse Quicklock nesting trays. The photo above shows 2 nesting tunnels. The upper tunnel shows a common sight. It looks like sawdust, but actually is a collection of pollen feeding mites amongst pollen. The lower tunnel contains a mason bee cocoon on the left hand side and a group of pupae on the right hand side. The whole cell with the pupae was very sticky. It looks like these insects have consumed a lot of the pollen/ nectar mixture that the female mason bee had collected for her offspring.
We have never seen this inside a mason bee nesting tunnel, and we are wondering what it is.
Photo #2 is a collection of fruit flies. Joe has never seen such persistant fruit fly activity as last year (2010). The question is whether these fruit flies are the same as the pupae in photo number one. If anyone knows if this is the new Cherry fruit fly, please let us know.